Typically an explosive charge for mining and other excavation activities is placed in a borehole. Frequently the charge is supported at a point below the surface, that is, it is supported at a desired depth in the borehole by an inflatable plug in the form of gas tight bag. The plug is lowered to a desired depth and inflated such that it becomes firmly engaged with the sides of the borehole. Typically an aerosol canister is used to inflate the bag, with the aerosol being locked on to inflate the bag when it is in position in the borehole.
The storage and use of aerosol canisters is subject to international and local standards relating to safety where the canister is classified as safe when not exposed to direct sunlight or temperature above 50 degree C. When exposed to temperatures above 50 degrees the canister can become stressed and good safety protocols will deem such a canister unsafe. In extreme conditions, such as temperatures above 70 degrees, the canister can explode.
At present personnel using such inflatable plugs have no ready means of determining the temperature of the canister, nor whether the canister has been exposed to dangerous temperatures. Similar problems exist for other dangerous goods for which an exposure to a temperature extreme can render them more dangerous or unsafe.
The present invention seeks to provide a solution to this problem.
Reference to prior art documents is not an admission that they form part of the common general knowledge of a skilled person in any jurisdiction.